After taking a second straight pole, Hamilton was able to complete a grid-to-flag victory, coolly dealing with Alonso's two attempts to pass him.

The Spanish world champion tried to hustle pole-sitter Hamilton off the grid but the rookie pulled away and used his now customary early pace to stretch his lead.

After making their first pit-stops just one lap apart, Alonso tried to pass Hamilton, who had become embroiled with the back-markers.

Alonso gathered pace in Hamilton's slipstream and the two McLarens went side-by-side down the main straight, only for Alonso to be thwarted by the Briton as they entered Turn One - after that tussle the McLarens did not race again.

The start was the key, after that who was second would be second in the race

Fernando Alonso

McLaren's build-up to Indy had been dominated by Alonso and Hamilton's publicly sniping about favouritism within the team.

When it came to the crunch team boss Ron Dennis wisely chose to bring both his drivers home safely and preserve the points.

Hamilton added: "It was very tough, Alonso fought very well but at the end I managed to pull a gap which I was able to maintain and control the race."

Alonso, whose glum expression indicated he took little comfort from his best-ever finish in the US, said he had lost the race right at the beginning.

"I think the start was the key point of the race, after that who was second would be second in the race," said Alonso, 25.

"My start was good but we both braked in more or less the same place. I tried to overtake but I didn't want my race to finish in the first corner.

"Eight points are better than nothing, we increased the gap on Ferrari which is one of the main things at this is point in the championship."

Hamilton's win in Indianapolis saw him become only the fourth rookie, alongside Jacques Villeneuve, Nino Farina and Juan Manuel Fangio, to win at least two races in their debut season.

Teenager Vettel got in the history books on his impressive debut

It was also an historic day in Indianapolis for Sebastian Vettel, who became the youngest driver to score a point.

The 19-year-old was making his debut for BMW Sauber as a replacement for Robert Kubica, who is still recovering from the effects of his high-speed crash in Montreal.

Vettel drove smartly and was bumped up into eighth after Nico Rosberg retired on lap 69 as smoke plumed out of his Williams, which was yet again haunted by reliability problems.

There were signs of encouragement for Renault as Heikki Kovalainen, who briefly led a race for the first time in his career, finished fifth ahead of Toyota's tenacious Jarno Trulli.

Mark Webber collected his first points of the season in seventh for Red Bull. There was less luck for Trulli and Webber's respective team-mates.

David Coulthard's Red Bull got shunted by Ralf Schumacher's Toyota out of Turn One on the opening lap, forcing both, along with Honda's Rubens Barrichello, to retire.

Jenson Button brought the other Honda home in 12th while fellow Briton Anthony Davidson was one place better off in his Super Aguri.

Results from the United States Grand Prix, Indianapolis Motor Speedway: